Interferon Type I Type I IFN protein
«Human type I interferon (IFNs) are a large subgroup of interferon proteins that help regulate the activity of the immune system.
Interferon bind to interferon receptors. All type I IFN bind to a specific cell surface receptor complex known as the IFN-α receptor (IFNAR) that consists of IFNAR1 and IFNAR2 chains.
Type I IFN are found in all mammals, and homologous (similar) molecules have been found in birds, reptiles, amphibians and fish species.» (wikipedia)